Finding compatible RBCs would be most difficult for patients with antibodies to which antigen?

Finding compatible red blood cells (RBCs) is particularly challenging for patients with antibodies to the Vel antigen because it is relatively rare in the general population. The Vel antigen is found on the surface of red blood cells, and individuals who are Vel-negative can develop anti-Vel antibodies if exposed to Vel-positive blood.

Because of its infrequency, obtaining compatible blood for a patient with anti-Vel antibodies can be quite difficult, as the majority of donated blood is likely to be Vel-positive. This situation necessitates thorough searching through blood bank inventories or even resorting to directed donations from individuals known to be Vel-negative.

In contrast, the other listed antigens may have more available compatible blood. Antibodies against more common antigens like D, C, E, or K might still pose challenges but usually have larger donor pools available. Similarly, antibodies to C or Fya, or Wra and Hta, would also have more readily available antigen-negative units due to their presence in a broader cross-section of the population compared to the Vel antigen. This makes finding compatible RBCs for Vel antibody-positive patients particularly complex within the context of blood banking.